/*
 * Copyright 2010 The Apache Software Foundation
 *
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.hadoop.hive.ql.exec.tez;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.hadoop.conf.Configurable;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.CommonConfigurationKeys;
import org.apache.hadoop.hive.ql.io.HiveKey;
import org.apache.hadoop.io.serializer.JavaSerialization;
import org.apache.hadoop.io.serializer.WritableSerialization;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.Partitioner;
import org.apache.hadoop.mapred.lib.TotalOrderPartitioner;
import org.apache.hadoop.mapreduce.MRJobConfig;

public class TezTotalOrderPartitioner implements Partitioner<HiveKey, Object>, Configurable {

	private static final Logger LOG = LoggerFactory.getLogger(TezTotalOrderPartitioner.class);

	private Partitioner<HiveKey, Object> partitioner;

	private static final String TEZ_RUNTIME_FRAMEWORK_PREFIX = "tez.runtime.framework.";
	public static final String TEZ_RUNTIME_NUM_EXPECTED_PARTITIONS = TEZ_RUNTIME_FRAMEWORK_PREFIX
			+ "num.expected.partitions";

	@Override
	public void configure(JobConf job) {
		if (partitioner == null) {
			configurePartitioner(new JobConf(job));
		}
	}

	@Override
	public void setConf(Configuration conf) {
		// walk-around of TEZ-1403
		if (partitioner == null) {
			configurePartitioner(new JobConf(conf));
		}
	}

	public int getPartition(HiveKey key, Object value, int numPartitions) {
		return partitioner.getPartition(key, value, numPartitions);
	}

	@Override
	public Configuration getConf() {
		return null;
	}

	private void configurePartitioner(JobConf conf) {
		LOG.info(TotalOrderPartitioner.getPartitionFile(conf));
		// make the HiveKey assumption
		conf.setMapOutputKeyClass(HiveKey.class);
		LOG.info(conf.get(CommonConfigurationKeys.IO_SERIALIZATIONS_KEY));
		// remove the Tez fast serialization factory (TEZ-1288)
		// this one skips the len prefix, so that the sorter can assume byte-order ==
		// sort-order
		conf.setStrings(CommonConfigurationKeys.IO_SERIALIZATIONS_KEY, JavaSerialization.class.getName(),
				WritableSerialization.class.getName());
		int partitions = conf.getInt(TEZ_RUNTIME_NUM_EXPECTED_PARTITIONS, -1);
		// get the tez partitioning and feed it into the MR config
		conf.setInt(MRJobConfig.NUM_REDUCES, partitions);
		partitioner = new TotalOrderPartitioner<HiveKey, Object>();
		partitioner.configure(conf);
	}
}